Flat plate collectors are the most commonly used type of collector. They are simple in design, reliable, relatively inexpensive and are used mostly for heating water. A typical solar thermal collector is just a metal box with a glass cover and copper or aluminum pipes running through it. These are capable of heating water or air as high as 180 degrees Fahrenheit.
A flat plate solar collector is usually made up of copper tubes attached to an absorber plate. The copper tubes are aligned in parallel running up and down the absorber plate. They are connected to each other by an inlet and outlet manifold. The entire assembly is enclosed within an insulated box and covered by glass or sun proof clear plastic.
Okay, here is how they work. Water flows into the inlet pipe, flows down and up (or up and down) through the black metal pipes (Flow tubes) that are attached to the metal backing (absorber plate) picking up heat from the suns rays that are streaming through the glass cover (glazing) and then out of the collector to a insulated storage tank (like a water heater).
The storage tank would be connected to your water heater so that when
the sun is not shining, your regular hot water heater can still function
and provide you with the hot water you need. Of course you can
minimize the use of your water heater by increasing the size of your
A solar water heater collector will last many years and will provide hot
water for your home with very little maintenance. They will usually
easily outlast your water heater and since the heated water is Free,
solar thermal panels pay for themselves in a relatively short time.